Effect of shrimp head protein hydrolysates on the state of water and denaturation of fish myofibrils during dehydration

ABSTRACT:   To utilize fisheries waste products as food materials with functional properties, shrimp head protein hydrolysates (SHPH) from three species of shrimp, that is, Northern pink shrimp ( Pandalus eous ), Endeavour shrimp ( Metapenaeus endeavouri ) and Black tiger shrimp ( Penaeus monodon ), were produced by enzymatic hydrolysis using endopeptidase derived from Bacillus subtilis and exopeptidase derived from Aspergillus oryzae at a level of 0.1% (w/w). SHPH were rich in protein (90–91%) and amino acids (71–84%) but little fat (0.01–0.02%). The average molecular weight of SHPH was 300–1400. The effect of 5% SHPH (dry basis) addition on the state of water and denaturation of lizard fish myofibrils (Mf) during the dehydration process was evaluated by the desorption isotherm and the Ca-ATPase activity, and compared with the effect of sodium glutamate (Na-Glu). SHPH decreased the water activity and the Ca-ATPase inactivation, and increased monolayer sorbed water and multilayer sorbed water of Mf, although these effects of SHPH were smaller than those of Na-Glu. These findings suggest that the SHPH suppressed dehydration-induced denaturation of myofibrillar protein by stabilizing the hydrated water surrounding myofibrils.     

南极磷虾主要过敏原的分离纯化及性质研究

为了探究南极磷虾致敏问题,从南极磷虾中筛选、鉴定、分离纯化其主要过敏原,并对过敏原的性质进行研究,实验通过缓冲盐溶液提取南极磷虾蛋白;采用SDS-PAGE和Western blot(WB)筛选南极磷虾过敏原;使用高效液相色谱-串联质谱鉴定过敏蛋白;通过等电点沉淀、硫酸铵盐析、阴离子交换柱层析分离纯化过敏原;采用SDS-...     

Cryoprotective effects of shrimp head protein hydrolysate on gel forming ability and protein denaturation of lizardfish surimi during frozen storage

ABSTRACT:   The effects of shrimp head protein hydrolysate (SHPH) from three species of shrimp (northern pink shrimp [ Pandalus eous ], endeavour shrimp [ Metapenaeus endeavouri ], black tiger shrimp [ Penaeus monodon ]) on gel forming ability and protein denaturation of lizardfish surimi during frozen storage at −25°C were evaluated. The quality of lizardfish surimi with 5% (dried matter) of any of the three SHPH or sodium glutamate (Na-Glu) was examined in terms of gel strength, whiteness, Ca-ATPase activity and the amount of unfrozen water, comparing with those of surimi without additive as the control. The residual Ca-ATPase activity and gel strength of surimi with SHPH were higher than those of the control throughout 180 days of frozen storage, regardless of shrimp species. The highest effect was found in surimi with Na-Glu. The gel strength and Ca-ATPase activity found a high positive correlation. The addition of SHPH to surimi also increased the amount of unfrozen water by approximately 1.29–1.36 fold higher than the control, however kamaboko gels of the control was significantly whiter. From these results, freeze-induced denaturation of lizardfish muscle protein could be lessened by the addition of SHPH, resulting in a high gel strength and Ca-ATPase activity.     

南极磷虾体内主要营养活性物质在热处理过程中的流向

虾粉是南极磷虾最主要的加工产品之一,加工过程中,热处理会造成营养物质的流失和活性物质的破坏,是决定虾粉品质最主要的影响因素。为了掌握虾粉加工过程中主要物质的变化情况及流向路径,通过测定蒸煮、干燥两个涉及到热处理的关键工序中水分、灰分、蛋白质、脂质等主要营养物质的含量变化及脂肪酸、虾青素等功能成分的损失情况,分析各主要物质的流向路径及变化原因。结果显示：水分在蒸煮过程中流失8.49%,干燥过程中水分流失63.5%,大多以蒸发的形式流失;蛋白质在蒸煮过程中流失1.12%,其中流向蒸煮液0.87%,流失部分主要为水溶性蛋白,干燥过程流失6.05%;脂质在蒸煮、干燥过程中分别减少1.11%和1.61%,进一步分析其脂肪酸组成,发现多不饱和脂肪酸含量由45.57%降低至43.65%,其中EPA相对含量在蒸煮、干燥过程中分别减少0.41%和1.16%,DHA相对含量在蒸煮过程中变化不大,干燥过程中减少0.68%;虾青素是热敏性物质,受热处理的影响,在蒸煮、干燥过程中分别减少29.4和58.6mg/kg;灰分含量在蒸煮、干燥过程中分别减少2.85%和0.85%;结果表明蒸煮过程损失的主要物质为蒸煮液中的可溶性物质及少部分的热敏性物质,干燥过程主要造成水分的蒸发和虾青素等热敏性物质的破坏。研究初步掌握了南极磷虾虾粉加工过程中主要物质的含量变化与流向路径,分析了变化原因及主要影响因素,并讨论提出了减少物质流失的方案,可为后续南极磷虾粉加工工艺流程和参数的优化提供理论依据,对提高虾粉品质、促进南极磷虾资源高质化利用具有非常重要的意义。     

Effect of Cryoprotectants on Suppression of Protein Structure Deterioration Induced by Freeze-thaw Cycle in Pacific White Shrimp

This study aimed to elucidate the changes in Pacific white shrimp (Litopenaeus vannamei) myofibrillar protein as influenced by multiple freeze-thaw cycles as well as the stabilization effects of sucrose and trisodium citrate on shrimp myofibrils. Shrimp myofibrils in 0.1 M NaCl, 20 mM Tris-HCl (pH 7.5) were mixed individually with sucrose and citrate at concentrations of 0.05 M and were evaluated for Ca²⁺-ATPase activity, salt solubility, total and reactive sulfhydryl, and surface hydrophobicity during three freeze-thaw cycles. Sucrose and citrate had strong cryoprotective effects against freeze denaturation by retaining higher Ca²⁺-ATPase activity and salt-soluble myosin and actin, by slowing the reduction of reactive sulfhydryl (SH) and by exposing less hydrophobic groups at the surface of the protein compared with the no-additive sample. Results indicated that both cryoprotectants had suppressive effect against protein denaturation and helped stabilize white shrimp myofibrillar protein during the freeze-thaw process. This study suggests that sucrose and citrate stabilized the protein structure by retarding the unfolding of protein; thus, the native protein could be protected during frozen storage.     

南极磷虾营养评价与安全性研究

对天然生长的南极磷虾肌肉中营养成分与营养品质进行了较全面系统的分析,并结合安全性进行了初步研究。结果表明,南极磷虾肌肉(干样)中粗蛋白含量64·44%,粗脂肪含量5·14%,粗灰分含量10·90%,无氮浸出物含量19·52%;18种氨基酸总量为57·16%,其中8种人体必需氨基酸含量为25·88%,占氨基酸总量的45·25%;必需氨基酸指数(EAAI)为54·94,其构成比例符合FAD/WHO的标准;4种鲜味氨基酸含量为23·06%,占氨基酸总量的35·98%;矿物质含量丰富;铅、汞、镉、砷几种重金属含量平均值均低于相关食品卫生标准限量。综合分析认为,南极磷虾是一种食用安全、营养价值较高的虾类,具有良好的开发利用前景。     

南极大磷虾木瓜蛋白酶酶解产物氟浓度及营养成分研究

为了解酶解处理对南极大磷虾木瓜蛋白酶酶解产物（上清干物质KSF,沉淀干物质KS和残渣KR）中氟浓度的影响,采用氟选择电极法对酶解产物中氟进行测定。同时,采用国标方法对KSF和KS中主要营养成分进行测定。结果：KR中氟浓度最高,且KR中氟占酶解前基质中总氟的质量分数为72.94%~79.94%,而KSF和KS中氟浓度得到极大的降低。木瓜蛋白酶加入有利于虾浆中不溶的蛋白质以可溶解的形式进入上清液中。KSF中未检测到粗脂肪,总糖含量为13.91%~21.57%,粗蛋白含量为57.75%~67.13%。而KS中粗脂肪含量高达33.28%~42.90%,总糖10.14%~15.57%,粗蛋白38.00%~44.87%。因此,木瓜蛋白酶酶解南极大磷虾获得的KS和KSF均可以作为优质、安全的饲料添加剂。其中,添加1.5%的木瓜蛋白酶和1.0%葡萄糖,经58℃水浴3 h的酶解方式能使KSF的得率从18.65%上升到20.37%,其粗蛋白含量为65.49%,而KS的粗蛋白和粗脂肪含量分别为39.16%和38.49%,为最佳的酶解南极大磷虾的酶解方式。     

Extracting Protein from Antarctic Krill (Euphausia superba)

ABSTRACT

The isoelectric solubilization/precipitation (ISP) process was applied to Antarctic krill protein extraction. The solubility of Antarctic krill proteins and their fluoride content were studied between pH 1.00–13.75. The previous krill protein extraction conditions using ISP were improved. Excess fluoride in Antarctic krill was removed using a water-washing method according to its solubility. To save water, a multistage countercurrent system was used to optimize the ISP method. The results showed that the solubility of Antarctic krill proteins reached a minimum at pH 4.5 and a maximum at pH 13.5, while the concentration of dissolved fluoride was relatively unchanged (16.78–20.50 mg/L), with pH 2.00–13.50. Water-washing 4 times could reduce fluoride 98.14 ± 0.01% from krill with about a 5.14 ± 0.21% protein loss. The reduction allows krill protein to meet the Chinese National Standard (GB 2762-2005) for fluoride. Meanwhile, the four-stage countercurrent system achieved almost the same high fluoride removal rate (98.58 ± 0.01%) using only 25% of the water.     

正交实验优化南极磷虾蛋白肽的纳滤脱盐工艺

为建立南极磷虾(Euphausia superba)蛋白肽纳滤脱盐工艺,以脱盐率和蛋白损失率为评价指标,通过单因素实验和正交实验对影响南极磷虾蛋白肽纳滤脱盐效果的主要因素(蛋白肽浓度、压力、循环次数)进行优化。结果显示,采用纳滤技术对南极磷虾蛋白肽进行脱盐处理的最佳工艺条件：蛋白肽浓度为3%、纳滤压力为1.2 MPa、循环次数3次,在该条件下,南极磷虾蛋白肽的脱盐率达到(86.35±2.11)%、蛋白损失率为(9.10±0.35)%。采用优化工艺获得的南极磷虾蛋白肽的盐分含量为(1.14±0.12)%,蛋白质含量为(92.73±2.29)%,相对分子质量主要分布于3000 Da以下,氨基酸组成合理且符合联合国粮农组织/世界卫生组织规定的标准。研究将为高品质南极磷虾蛋白肽产品开发提供技术支撑。     

The efficacy of ingredients included in shrimp feeds to stimulate intake

The inclusion in feed formulations of ingredients that act as attractants and feeding incitants or stimulants has been proposed as a means of increasing feed consumption, and hence growth, of farmed shrimp. Squid, crustacean and krill meals, fish and krill hydrolysates and a betaine product (Finnstim) were examined to assess their relative effectiveness in increasing the feed intake of black tiger shrimp Penaeus monodon. These presumed feeding effectors were added to a base feed at between 5 and 50 g kg^?1. Given a choice between the base feed and one containing one of the test ingredients, P. monodon showed a significantly greater preference for the feeds containing crustacean or krill meal. Four of the presumed feeding effectors were further evaluated in a growth response experiment. There was no significant difference in the amount the shrimp consumed of any of the feeds. However, the growth rate of the shrimp was about 20% faster on the feeds containing crustacean meal or krill meal. Although ingredients such as crustacean meal or krill meal can improve feed intake, in practical feed formulations that contain significant amounts of terrestrial protein but relatively low levels of marine ingredients, there does not appear to be need for additional feeding effectors. However, crustacean meal and krill meal do provide a significant nutritional benefit, as seen by the improved growth rates in this study.     

海冰与南半球环状模对南极布兰斯菲尔德海峡南极磷虾种群结构的影响

南极磷虾(Euphausia superba)是南大洋生态系统的关键物种,其生活史各阶段的生理过程与海冰密切相关。本研究基于开放获取数据库计算了布兰斯菲尔德海峡内反映南极磷虾种群结构特征的5个参数,包括补充指数和幼体、雌性、雄性平均体长以及雌性个体占比,并结合布兰斯菲尔德海峡及周围3个水域的海冰面积、水深、海底复杂度以及南半球环状模(SAM)逐日指数构建广义加性模型,探讨了海冰与气候事件对磷虾种群动态的影响。结果表明,磷虾幼体、雄性磷虾平均体长与60日前的威德尔海西北部海域海冰面积呈显著的负相关,磷虾补充指数与当日和60日前的SAM呈显著的正相关。随着海底复杂性的增加,磷虾补充指数显著下降。4个海域的海冰面积变化对磷虾补充指数和其他种群特征指标的影响存在差异。     

南极磷虾粉加工过程中虾青素的含量、结构及抗氧化性

虾青素由于结构稳定性较差，在高温条件下易降解和异构化。为了掌握南极磷虾粉加工过程中虾青素含量、结构及抗氧化能力的变化情况，采用高效液相色谱法测定虾青素在各加工阶段的含量及结构变化，对比虾青素在各加工阶段的抗氧化性差异，分析虾青素结构与功能活性的相关性。结果显示，南极磷虾原料中虾青素含量为110.6 mg/kg，其中全反式结构虾青素占比90.7%,13-顺式虾青素和9-顺式虾青素占比分别为4.7%和4.6%，经过蒸煮和干燥后，虾青素含量分别为88.7和52.1 mg/kg，全反式虾青素占比分别为76.2%和72.2%,13-顺式虾青素占比分别为19.9%和21.9%,9-顺式虾青素占比分别为3.9%和5.9%。南极磷虾原料中虾青素的3S, 3′S,3S, 3′R和3R, 3′R三种光学异构体含量分别为16.8、17.9和72.1 mg/kg，蒸煮后分别为12.0、25.5和55.3 mg/kg，干燥后分别为2.8、8.1和12.4 mg/kg。各阶段虾青素清除DPPH自由基能力均显著强于Vc，在羟基自由基清除实验中，蒸煮和干燥后的虾青素抗氧化能力强于原料中的虾青素，在FRAP铁离子还原实...     

南极磷虾粉对大菱鲆生长、非特异性免疫及氟残留的影响

以鱼粉、南极磷虾粉和豆粕为蛋白源,以南极磷虾粉蛋白分别替代饲料中的0(对照组)、20%、40%、60%的鱼粉蛋白制成4种等氮等能的饲料,并以此饲料饲喂大菱鲆(37.36±2.12g)56d。试验结果显示,饲料中南极磷虾粉水平对大菱鲆的成活率及特定生长率(SGR)没有显著性影响(P>0.05);对各组的饲料干物质表观消化率均有显著性影响(P<0.05),替代40%组与替代60%组蛋白质表观消化率较对照组有显著性差异(P<0.05);对大菱鲆血清中的碱性磷酸酶(AKP)、酸性磷酸酶(ACP)、溶菌酶及总超氧化物歧化酶(T-SOD)活力无显著性影响(P>0.05)。大菱鲆各组间肌肉中氟残留量没有显著性差异(P>0.05),且肌肉中氟含量均在可食用范围内,大菱鲆各组间骨骼中氟残留量均有显著性差异(P<0.05)。     

南极磷虾产品研究及发展趋势

南极磷虾生活在南极海域,资源量丰富,具有较高的应用价值.南极磷虾开发耗资巨大,在大规模商业性开发投入之前,做好相关产品与市场分析等基础工作十分必要.本文首先对南极磷虾产品的发展历程进行了分析,继而对南极磷虾产品的主要形式与发展前景进行了剖析,并对主要目标市场进行了定位研究.研究认为：南极磷虾粉和液态磷虾油是目前较为普遍的产品存在形式.其中,磷虾粉可作为蛋白质增强剂、增味剂和重要的氨基酸补充剂使用,可作为渗透调节之用,同时,可以作为矿物质来源、脂质来源、几丁质/几丁聚糖免疫增强剂、天然色素（类胡萝卜素）来源使用.磷虾粉的目标市场更倾向于水产饲料;磷虾油的目标市场主要倾向于营养保健和制药行业.相对于磷虾粉,磷虾油的市场价值更高.     

南极磷虾(Euphausia superba)脂肪与蛋白含量的季节变化

为了有效提取营养功效和附加值均更高的磷虾油,对南极磷虾(Euphausia superba)资源的综合开发利用提供参考,利用2013年7-8月和2013年12月-2014年5月在南乔治亚群岛和南设得兰群岛附近海域采集的南极磷虾样品,采用索氏抽提法,分别用无水乙醇、丙酮、石油醚、正己烷、乙酸乙酯、环己烷6种常见的有机溶剂作为提取试剂,对南极磷虾体内的脂肪进行提取,并确定最佳萃取溶剂.同时对南极磷虾脂肪、蛋白含量的季节变化及其与体长的关系进行了分析.结果显示,无水乙醇为南极磷虾脂肪提取的最佳溶剂.南乔治亚群岛海域7-8月南极磷虾脂肪含量和蛋白含量(干重)分别为(22.03±0.51)％和(64.52±0.16)％;其中,全长小于40 mm的磷虾个体,脂肪与蛋白含量均显著高于全长大于40 mm的个体(P＜0.05).从南极的初夏到秋末,南设得兰群岛海域的南极磷虾脂肪含量呈逐渐上升趋势,由12月的(19.83±0.04)％上升至翌年4月的最大值(30.584±0.02)％;5月则略有降低,为(28.66±0.03)％.与此相反,南极磷虾的蛋白含量则是12月最高、4月最低,分别为(66.75±0.14)％和(58.02±0.23)％;脂肪含量与蛋白含量呈显著负相关(P=0.005).研究结果对南极磷虾渔业及其生产安排具有直接的指导意义.     

Spatial distribution of Antarctic minke whales (Balaenoptera bonaerensis) in relation to spatial distributions of krill in the Ross Sea,Antarctica

The spatial distribution of Antarctic minke whales in the Ross Sea with relation to spatial distributions of their prey – krill – was investigated in this study using generalized additive models (GAMs). Spatial distributions of two species of krill (ice and Antarctic krill) were estimated by GAMs. Three abiotic factors – distance from the continental shelf break (800 m isobaths), the mean temperature and salinity from the surface to 200 m (MTEM‐200 and MSAL‐200), and latitude and longitude – were used as covariates for models of krill. Estimated spatial distributions of krill were then used with other covariates to model the spatial distribution of Antarctic minke whales. In the selected model of Antarctic minke whales, Antarctic krill were more influential than ice krill. The number of Antarctic minke whales increased as the density of Antarctic krill increased to around 1.5 g m^?2. Beyond that, the number of Antarctic minke whales decreased as the density of Antarctic krill increased. High densities of the Antarctic minke whales were estimated along the sea ice edge in the eastern part of the Ross Sea. Specifically, the densities were high in the north of the continental shelf break where low MTEM‐200 and MSAL‐200 and intermediate densities of Antarctic krill were observed. Further data collection is needed to investigate interannual variations and trends in their relationship. The results show that the spatial distribution of Antarctic minke whales is a function of longitude, distance from the shelf break, oceanographic condition (temperature and salinity), and densities of ice and Antarctic krill.     

南极磷虾中氟含量迁移影响因素研究进展

南极磷虾(Euphausia superba)以其庞大的生物量和潜在的渔业资源价值广泛受到世界各国的重视.南极磷虾因富含蛋白质已成为人类重要的优质生物蛋白库,此外,其还含有脂质、矿物质等营养物质、虾青素及甲壳素等活性物质.目前,高氟含量一直是制约南极磷虾大规模加工利用的瓶颈.南极磷虾在加工利用过程中伴有氟元素的迁移现象...     

Nutritive value of squid and hydrolyzed protein supplement in shrimp feed

Though some protein sources like squid and protein hydrolysates are assumed as growth enhancers for shrimp, little is known about the biochemical basis of this phenomenon. Low, heat-dried squid (Dosidicus gigas) (SQ) and two commercial protein hydrolysates from fish (FH) and krill (Euphasia sp.) (KH) were assayed in feeding trials with Penaeus vannamei. Feeds were prepared with the tested proteins at 3%, 9%, and 15% of the total crude protein. A total of nine experimental feeds plus a commercial one as control (C32) were tried. Additionally, digestibility in vivo and in vitro was evaluated. Survival was not different among groups. Weight gain of shrimp and total and specific proteolytic activity for trypsin and chymotrypsin were affected by type and quantity of supplemented protein. In vivo and in vitro digestibilities were also influenced by the source and quantity of the protein supplement. Shrimp fed feed with FH at 3% protein supplementation grew more than those fed with higher supplementations. Groups fed SQ had similar results as those fed FH, and gained more weight when fed the lowest SQ quantity. SDS-PAGE showed a large concentration of small peptides in SQ, which may explain results similar to FH. KH enhanced shrimp growth at all supplementations and had a lower degree of hydrolysis (DH) than FH. SQ also demonstrated good growth performance, but better at the lower supplementation, probably because of the presence of small peptides and possibly free amino acids from protein hydrolyzed by endogenous enzymes in the squid mantle. We conclude that hydrolyzed protein is a good supplement for shrimp feeds, but it must meet specific requirements for adequate assimilation.     

南极磷虾中层拖网捕捞参数对CPUE变动的影响

根据中国在南极海洋生物资源养护委员会(CCAMLR)48.1亚区和48.2亚区内2010—2014年南极磷虾拖网渔船的捕捞数据,采用广义可加模型(generalized additive model, GAM)分析各拖网捕捞参数(因子)对南极磷虾汛期单位捕捞努力量渔获量(catch per unit effort, CPUE )的影响。结果表明:2010—2014年我国南极磷虾作业渔场主要位于南极半岛等岛屿的周边海域,CPUE 值月变化明显,2—5月为捕捞高峰期。 CPUE 最高值为2014年,最低值为2012年,年平均CPUE呈略上升趋势。从月变化来看,除6月外,标准化 CPUE 均大于名义 CPUE;且最大值出现在4月或5月,最小值均出现在10月。GAM分析表明各捕捞参数对 CPUE 的影响由大到小依次为:拖网速度、网口高度、网口水平扩张、拖曳水深、曳纲长度;各因子的偏差解释率分别为22.8%、14.5%、12.7%、6.0%、1.6%,所有因子对 CPUE 的总体偏差解释率为57.6%。研究认为,我国南极磷虾捕捞作业中最适拖网速度范围2.6~3.1 kn;最适网口高度范围22~30 m;最适网口水平扩张范围20~25 m;最适曳纲长度范围100~200 m;最适拖曳水深范围0~40 m。     

南极磷虾粉营养成分的分析与比较

对两种不同来源的南极磷虾粉营养成分进行了分析和评价,并与进口鱼粉的营养成分进行了比较。结果显示,上海开创远洋渔业有限公司开利轮产南极磷虾粉(磷虾粉S)粗蛋白含量为62.89%,高于辽宁远洋渔业有限公司安兴海轮产南极磷虾粉(磷虾粉D)和进口鱼粉的粗蛋白含量,两种磷虾粉粗蛋白质含量分别达到一级品和二级品指标。磷虾粉S、磷虾粉D和进口鱼粉18种氨基酸总量分别为66.36%、57.19%、67.24%,鲜味氨基酸含量较高分别为24.65%、20.69%和25.25%,8种必需氨基酸含量分别为31.43%、21.74%、25.62%,且磷虾粉S必需氨基酸含量明显高于磷虾粉D和鱼粉,磷虾粉S、磷虾粉D和进口鱼粉三种样品必需氨基酸指数(EAAI)分别为57.83、49.89、57.07;磷虾粉S、磷虾粉D和进口鱼粉三种样品脂肪酸中,多不饱和脂肪酸含量较高分别为43.28%、40.25%、46.58%,且磷虾粉S的EPA与DHA的总量(36.14%)高于磷虾粉D(31.30%)及鱼粉(27.65%)。分析结果表明,南极磷虾粉蛋白含量高,且氨基酸组成符合FAO/WHO推荐的蛋白质理想模式,含有丰富的多不饱和脂肪酸,营养价值较高,具有较大的开发利用前景。